This invention relates to an exhaust gas change-over apparatus for use in dump trucks or the like.
The dump trucks each has an exhaust gas change-over device mounted thereon which is adapted to introduce and discharge the engine's exhaust gas into a plurality of hollow ribs of a vessel when the vessel is at its normal carry position (that is; the vessel is placed on and supported by the vehicle body) and to discharge the exhaust gas toward the side of the vehicle when the vessel is at its dump position (that is; the vessel is inclined at its maximum angle relative to the vehicle body so as to unload the cargo therein).
As for the exhaust gas change-over device of the kind specified, there has heretofore been known and employed a device comprising a box having one side wall formed with an exhaust gas inlet which is connected to an engine's exhaust gas outlet (exhaust pipe), an upper wall to which is fixedly secured a second outlet pipe adapted to introduce the exhaust gas into the hollow ribs of the vessel and another side wall to which is fixedly secured a first outlet pipe adapted to introduce and discharge the exhaust gas to the side of the vehicle, and a shutter pivotally mounted in the box so as to enable either one of said first and second outlet pipes to be selectively blocked or shut off.
This construction, however, is disadvantageous in that because the hub portion of the shutter is pivotally mounted on and carried by support shaft through its bearing, it is unable for the shutter to contact tightly with the end faces of the first and second outlet pipes because of the presence of a deviation in dimensions thereof when manufactured, and also because of the generation of idle plays of the bearing and hub portion produced by the wear down thereof resulting from their use for an extended period of time, thereby forming clearance therebetween through which the exhaust gas is allowed to leak.
As for the prior art to overcome such difficulties, there has been proposed a device in which a lever is connected to a support shaft and a shutter is pivotally mounted on the lever so that the shutter can be brought into close contact with the end face of either one of the first and second outlet pipes irrespective of the presence of idle plays and deviation in dimensions when manufactured.
However, this construction is also disadvantageous in that because of the need for forming a notch in the first outlet pipe through which the lever is allowed to pass, the exhaust gas tends to leak through the clearance between the notch and the lever when the vessel is held at its normal carry position (that is; when the shutter blocks or shuts off the first outlet pipe).
Further, there are two types of dump trucks; in one type, the engine exhaust pipe is connected to the side wall of the box of the exhaust gas change-over device, and in another type, the exhaust gas pipe is connected to the bottom wall of the box. Because of differences in the shapes of the shutter and the first and second exit pipes between the two types, it has heretofore been necessary to provide two kinds of exhaust gas change-over devices. cl SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a change-over apparatus of exhaust gas which is capable for effectively preventing gas leakage and assures a reliable change-over of exhaust gas.
Another object of the present invention is to provide a change-over apparatus of exhaust gas which has two gas inlets formed in a side and bottom walls of a housing and in which exhaust gas from an engine can be selectively introduced through either one of the gas inlets.
In accordance with an aspect of the present invention, there is provided a change-over apparatus of exhaust gas for use with a vessel of a dump truck having an exhaust pipe connected to an engine of the dump truck, said vessel having a plurality of hollow ribs integrally formed therewith, the change-over apparatus comprising: a box-like housing having a first inlet for exhaust gas formed in a first wall thereof, a first outlet for the exhaust gas formed in a second wall thereof and a second outlet for the exhaust gas formed in a third wall thereof, the second and third walls being arranged at right angles with each other; a first pipe mounted in the first outlet and open to the atmosphere; a second pipe mounted in the second outlet; a third pipe telescopically mounted on the second pipe, said third pipe having a flange fixedly secured thereto and being connectible with the hollow ribs of the vessel when said vessel is in its carry position; shutter means for selectively closing said first and second pipes, the shutter means being pivotally mounted to a fourth and a fifth walls of the housing, said fourth and fifth walls being opposed against each other; a pair of means each operatively associated with the shutter means for causing the shutter means to selectively close the first and second pipes; and first spring means disposed between the flange of the third pipe and the third wall for biasing said third pipe toward its raised position thereby urging the shutter means to close the second pipe; whereby said third pipe is movable between the raised position and a lowered position where said vessel is contacted with top end of the third pipe and said shutter means is urged to close the first pipe.
The above and other objects, features and advantages of the present invention will be readily apparent from the following description taken in conjunction with the accompanying drawings.